Sunday, December 14, 2014

Does eating out put us at risk of too much unhealthy stuff, even if we avoid McDonald's, Burger King & Co? Recent study says: Yes it does!

When I woke up today, I thought it would be nice to do some short news and get rid of a handful of studies in my "to be written about in the future" folder. What about the U-shaped dose-response curve for the cardio-protective effects of vitamin C, for example?

In their latest paper in the Proceedings of the Nutrition Society scientists from the Queen’s University Belfast and the MONICA Institutes in Belgium and France report that there is a U-shaped dose-response relationship between vitamin C intakes and cardiovascular disease (CVD) and mortality risk in the ~10,000 50–59 year-old Irish, Belgian and French men who participated in the PRIME study from 1991–1993 (Lyner. 2014).

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Said study had originally been designed to examine the substantial differences in cardiovascular incidence and mortality between Northern Ireland and France.

The data is based on blood samples that were taken from participants at baseline, stabilised and frozen at −150°C and complemented by additional follow ups every year. Over the total study duration of 10 years, the scientists lost only 5% of their subjects due to non-compliance.

Figure 1: Changes in overall mortality risk and CVD risk in the 2nd to 4th quartile of serum vitamin C levels; only the risk reductions in the third quartile were statistically significant (Lyner. 2014)

The relevant data, the graph in Figure 1 is based on stems from those 6.2% (n= 654) who died, and the 5.2% (n= 546) who had a CVD event that was validated by a medical committee.

What do previous studies say? Randomized controlled trials did not show significant reductions in mortality risk with vitamin C supplementation (Bjelakovic. 2007). A subsequently published Cochraine Review even found slight reductions in all-cause mortality in healthy individuals who use vitamin C supplements (+2%; Bjelakovic. 2012). Higher total vitamin C intakes from food have yet been linked to 35% and 10% reductions in all-cause mortality risk in US men and women, respectively (Enstrom. 1992).

As you can see, the vitamin C levels in the blood, which were measured on a BMG FLUOstar Optima plate reader predict the risk of overall mortality and CVD incidence the risk at both high and low levels. In that, it should be obvious that you're far worse off with "no" vitamin C in your blood than you'd be with very high levels. And still, the fact that the happy (high) medium, i.e. vitamin C levels in the 3rd quartile, was associated with the most significant risk reduction, provides additional evidence that having as much as possible of a good thing is not necessarily optimal.

I'd love to see data on supplementation and / or nutrition practices, but unfortunately (or luckily? due to accuracy) the study at hand is based on serum measures, only. Overall, the data still speak in favor of the scientists' hypothesis that "increasing vitamin C status [and I would add 'by eating high vitamin C foods, like fruits and vegetables'] in the population could contribute to reduced rates of mortality" (Lyner. 2014).

Speaking of fruits and vegetables! Those are obviously not available at US restaurants.

I bet that the subjects in the "restaurant eater" group in a recent study from the American Cancer Society and the University of Illinois at Chicago did not consume exactly much of these healthy food items (fruits and vegetables). What they ate, on the other hand, were significantly more salt, saturated fat and total kcal.

More energy, less nutrients: Previous
studies based on datasets from 1994–1996 indicate that adults who
reported eating fast food had higher intakes of energy, total fat,
saturated fat, Na and carbonated soft drinks, and lower intakes of
vitamin A, vitamin C, calcium, iron, fibre, milk, fruits and vegetables
than those who did not report eating out - fast food or not (Paeratakul. 2003;
Bowman. 2004, Lachat. 2012).

If you look at the comparison of fast food and full-service restaurants, you may be surprised to see that the former are comparably harmless, when it comes to salt (remember: it's probably not an issue for most of us). I guess that is a result of the implementation of "salt reduction practices" in response to public pressure.

What's almost shocking and offers a look ahead into Americas future is the fact that the negative effects of eating out are significantly more pronounced in young adults (aka future diabetics). Similar negative trends are obvious for black (296kcal / 277kcal in fast food and full-service restaurants) vs. white & hispanic Americans (~180kcal) and people with middle & low (~230kcal extra) vs. high income (~160kcal extra).

In the discussion of their results, Nguyen and Powell point out that their research also suggests that restaurant food consumption as a snack was associated with particularly high additional energy intake, i.e. 260.99 kcal for fast-food and 234.20 kcal for full-service restaurants. It is thus only logical that they advise "that adults do not sufficiently reduce non-restaurant intake to compensate for additional energy intake on days consuming at restaurants." (Nguyen. 2014).

Vitamin C + E supplements block the adaptational response to exercise, but appear to boost fat loss, recent study shows - seems like you just cannot have it all | learn more.

Bottom line: Personally, I find none of the the previously presented study results surprising. Well, maybe the fact that full-service restaurants have people overeat even more than fast food restaurants.

The fact that very high vitamin C levels were associated with lower reductions in all-cause mortality and cardiovascular incidence risk, on the other hand, is something that shouldn't surprise you in view of the evidence from experimental trials on the non-existing benefits of vitamin C supplementation and the fact that the study participants in the "very high" vitamin C level quartile four of the study by Lyner et al. probably didn't get there due to their exuberant fruit and vegetable consumption | Comment on Facebook!

Bowman, Shanthy A., and Bryan T. Vinyard. "Fast food consumption of US adults: impact on energy and nutrient intakes and overweight status." Journal of the American College of Nutrition 23.2 (2004): 163-168.

Enstrom, James E., Linda E. Kanim, and Morton A. Klein. "Vitamin C intake and mortality among a sample of the United States population." Epidemiology 3.3 (1992): 194-202.

Lachat, Carl, et al. "Eating out of home and its association with dietary intake: a systematic review of the evidence." Obesity Reviews 13.4 (2012): 329-346.

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